Microsoft has shipped Windows 11 Insider Preview Build 26200.5742 (KB5064075) to the Dev Channel, packing a new mobile device companion right inside the Start menu and quietly moving another batch of legacy settings into the modern Settings app. The August 8, 2025 release also delivers tangible performance gains in File Explorer and squashes a laundry list of bugs—though it comes with its own set of known gremlins that Insiders should watch for.

Dev Channel builds are the bleeding edge of Windows development, where experimental features and foundational changes land first. Build 26200.5742 continues Microsoft’s relentless push to modernize the OS while tightening integration with mobile devices. For anyone running a Dev Channel machine, here is everything you need to know about what’s new, what’s fixed, and what’s still broken.

A Mobile Companion Moves into the Start Menu

The marquee feature this time around is the redesigned mobile device companion panel inside the Start menu. When you click or tap the new layout, a flyout appears showing your most recent phone activities: missed calls, unread messages, recent photos, and even pending app updates. It’s a natural extension of the Phone Link experience that Microsoft has been refining for years, but bringing it directly into the Start menu eliminates the need to juggle separate apps or dig through the systray. The idea is simple: your phone’s most important moments should be as accessible as your local apps and documents.

The companion panel doesn’t replace the full Phone Link app. Instead, it’s a lightweight, glanceable surface that surfaces the few things you are most likely to want instantly—like replying to a text or seeing who just called. Behind the scenes, it uses the same connection infrastructure that already syncs notifications, calls, and photos between your phone and PC. Currently, Android devices benefit from the richest integration, though iOS support through the updated Phone Link with Bluetooth provides a subset of features. The Start menu companion respects the same privacy and notification settings you’ve configured in Phone Link, so nothing appears there that you haven’t already allowed.

Insiders have already begun testing the feature, and early chatter on the Windows Forum suggests that it is surprisingly snappy—pulling up recent items almost instantly. However, some users note that the companion panel can look a bit sparse if you haven’t used Phone Link recently, which may lead to a somewhat empty flyout. Microsoft has hinted that future builds could expand the companion to show battery status, hotspot toggles, and even a clipboard bridge. For now, it is a welcome step toward a truly unified PC–phone workflow, and one that feels right at home in the Start menu.

The Great Control Panel Migration Keeps Rolling

Perhaps the most unsung but strategically important change is the continued migration of time and language settings from the ancient Control Panel to the Settings app. With Build 26200.5742, administrators and power users can now perform a half-dozen tasks that previously required a trip to the old-style panels—all within the clean, modern confines of the Settings app.

Specifically, the following are now available under Settings > Time & language:

  • Adding additional clocks for different time zones is now under Date & time, no longer hidden in the legacy “Additional Clocks” dialog.
  • Configuring the Network Time Protocol (NTP) server—useful for domain-joined machines or anyone who wants to sync with a custom time source—has moved to the same page.
  • Customizing AM/PM symbols and the format of numbers and currencies no longer requires digging through the Control Panel’s Region applet.
  • Enabling Unicode UTF-8 for worldwide language support, a setting critical for developers and multilingual users, is now a simple toggle in the Settings app.
  • The ability to copy your current language and region settings to the welcome screen, system account, and new user accounts has finally been decoupled from the Control Panel, streamlining device setup and kiosk configurations.

This migration may feel incremental, but it represents another nail in the coffin for the Control Panel. Microsoft has been on a multi-year journey to deprecate the legacy console, and every piece moved into Settings makes Windows just a little more cohesive. Insiders who rely on these settings will appreciate that they are now searchable and consistent with the rest of the Settings interface, complete with keyboard navigation and accessibility improvements. The old Control Panel paths still exist for now, but Microsoft’s direction is clear: eventually, everything will live in Settings.

On the Windows Forum, seasoned admins have welcomed the move, though some caution that the new UI for NTP configuration needs better documentation. A few testers reported that the “Copy settings” option does not always carry over custom number formats reliably, a quirk that will likely be ironed out before this build reaches the Beta or release channels.

File Explorer Finally Feels Faster

File Explorer has been a persistent pain point for Windows 11 users, especially those with OneDrive or SharePoint synced folders. Build 26200.5742 addresses that head-on with performance improvements specifically targeting cloud file operations. Launching a file stored in the cloud and waiting for it to download on demand should now feel noticeably snappier. Context menus—which could sometimes struggle to populate when you right-clicked a cloud-only file—load faster and more reliably.

Microsoft’s release notes highlight two areas: the speed of initiating cloud file downloads when you open a folder, and the responsiveness of context menus that contain cloud-specific commands like “Free up space” or “Always keep on this device.” In practice, users should experience less of that frustrating pause when navigating folders full of online-only files. This is a direct outcome of optimizations to the Windows Cloud Files API, which now prioritizes metadata fetching and caches more aggressively.

The build also fixes several lingering File Explorer bugs: icon mirroring issues when using right-to-left languages (such as Arabic or Hebrew) have been resolved, and tooltips that stubbornly refused to disappear no longer linger on screen. One particularly annoying glitch where File Explorer would display an incorrect free-space color in dark mode—making low-space drives appear healthy—has been fixed, though a related color discrepancy in dark mode for low-space drives remains a known issue.

A Long List of Fixes

Beyond the headliners, KB5064075 includes a host of reliability and quality fixes that address crashes, input problems, and accessibility gaps:

  • Start Menu itself received multiple corrections, including one where categories (like “Productivity” or “Creativity”) displayed incorrectly, and another that caused some Visual Studio-related shortcuts to appear in the wrong section.
  • Task Manager, the essential tool for monitoring system performance, gets a stability boost. Crashes when switching tabs or ending certain processes have been fixed, and Microsoft improved keyboard focus behavior so that navigating with the Tab key is more predictable. These changes make Task Manager friendlier for users who rely on screen readers or other assistive technologies.
  • Input improvements benefit both Chinese IME users and those who use the touch keyboard. The Chinese IME no longer hangs when switching between candidates in specific apps, and the touch keyboard now correctly appears when you tap in a text field on a tablet, even after resuming from sleep.
  • Settings app crashes when adding a security key under Sign-in options (a critical path for password-less authentication) are now resolved.
  • Under the hood, a couple of low-level bugs have been squashed: apps that referenced the legacy dao360.dll database engine no longer crash on launch, and a SYSTEM_SERVICE_EXCEPTION bugcheck triggered by certain driver interactions has been eliminated.

Each of these fixes may seem minor individually, but collectively they smooth out the rough edges that can make daily Windows use frustrating. Insiders who had been hitting these issues in previous 26200-series builds will notice a more polished experience after installing KB5064075.

Known Issues: What’s Still Broken

No Dev Channel build is without its thorns, and 26200.5742 carries several documented problems that testers should be aware of before they hit the update button.

  • Installation rollbacks: Some users may see the update fail with error 0x80070005 and be rolled back to the previous build. This is often permission-related, and Microsoft recommends running the update troubleshooter and ensuring that the Windows Update service has full access to system folders. If you hit this, retrying after a clean boot often helps, but it’s a frustrating first-run experience.
  • Click to Do (Preview)—a new feature aimed at context-sensitive actions—remains in a rough state. Text and image actions sometimes do nothing, and in some cases the feature crashes outright. Since it’s a preview, this is expected, but early adopters excited about the tool should temper their expectations.
  • Start Menu layout: On first sign-in after updating, some Insiders have reported seeing a smaller, condensed Start menu layout that overwrites their custom tile arrangement. It’s temporary and reverts after a restart or a few minutes, but it can be disorienting.
  • Taskbar & System Tray: A handful of testers have noted that pinned apps vanish from the taskbar after the update, requiring manual re-pinning. This isn’t universal, but if you rely on a highly customized taskbar, you might want to snap a screenshot of your layout before upgrading.
  • File Explorer dark mode: While the free-space color bug was fixed, another dark-mode glitch persists. Drives that are critically low on space may still show an incorrect color in the graph view under This PC, making it harder to spot storage issues at a glance.
  • Live Captions on Copilot+ PCs: For devices with neural processing units (NPUs) that support on-device AI, using live captions with translation currently crashes the captions window. This is a known issue for Snapdragon X Elite and Intel Meteor Lake devices that leverage NPU-accelerated translations.
  • Xbox Controller over Bluetooth: Gamers beware—connecting an Xbox Wireless Controller via Bluetooth while build 26200.5742 is running can trigger a blue screen of death (bugcheck). The workaround is to use a wired USB connection until Microsoft ships a fix.

Microsoft is actively collecting feedback on all these issues via the Feedback Hub. If you run into any of them—or spot a new one—heading to the hub and logging a detailed report is the fastest way to get attention from the engineering team.

Community Pulse and What to Expect Next

Even though the official release notes are the primary source for this build’s contents, the Windows Forum community has been dissecting 26200.5742 with the usual mix of enthusiasm and healthy skepticism. Enthusiasts commend the mobile companion’s potential but want tighter integration with third-party Android launchers and Samsung DeX-style desktop extensions. Others appreciate the Settings migration but worry that Microsoft hasn’t yet committed to a full Control Panel deprecation timeline, leading to a half-way house that can confuse less technical users.

Performance improvements in File Explorer are unanimously welcomed, especially among Insiders who manage large SharePoint libraries. A few power users have run quick benchmarks and report that cloud file enumeration in a folder with thousands of items is roughly 30% faster than in the previous Dev build. It’s an early, anecdotal metric, but if borne out, it represents a meaningful quality-of-life upgrade for anyone drowning in cloud files.

The known issues list is longer than some would like, but that’s par for the course in a Dev Channel release. The warning about Xbox controller Bluetooth crashes has already sparked a Reddit thread, with gamers swapping workarounds. The error 0x80070005 during installation seems to correlate with machines that have certain third-party security software installed, pointing to a permissions conflict that Microsoft will need to address in a servicing update.

Looking ahead, features like the mobile companion and deeper Settings migration are expected to percolate into the Beta Channel in the coming months, eventually finding their way into a stable Windows 11 release—likely the 24H2 or later feature updates. The Dev Channel remains the fastest track for feedback, so if you’re opted in, your voice directly shapes the final product.

The Bottom Line

Windows 11 Insider Preview Build 26200.5742 isn’t the flashiest release, but it’s a solid workhorse update. The mobile companion in Start answers a real need for phone–PC convergence, the relentless march of settings migration simplifies system administration, and File Explorer finally gets the performance attention it deserves. The bug fixes reaffirm Microsoft’s commitment to reliability, even as the known issues remind us that this is still pre-release software.

For Dev Channel Insiders, hitting “Check for updates” now is a good idea—just be prepared for the possibility of a rollback and keep an eye on those taskbar pins. As always, your Feedback Hub reports are the fuel that powers the next wave of improvements.